Storm & Convective Discussion April 2016 Onwards

[Weather-history]

Overnight wintry showers

 

[Nick F]

Storm & Convective Forecast

Issued 2016-04-29 08:39:15

Valid: 29/04/2016 0600z to 30/04/2016 0600z

CONVECTIVE FORECAST - FRIDAY 29TH APRIL 2016

Synopsis

Surface low will drift slowly away from NE England across the North Sea today  beneath slow-moving upper low. Wrap around occlusion will bring further sleet or snow to SE Scotland & NE England, while upper cold pool associated with upper low pushes southward across, Ireland, England and Wales ... spreading bands of showers/scattered thunderstorms south during the day.

... N. IRELAND, EIRE, WALES, ENGLAND and SCOTLAND  ...

Pool of unseasonably cold and dry mid-upper air is evident as a dark stripe pushing south on WV imagery ... this is steepening lapse rates and destabilising the atmosphere and will bring bands of heavy showers, some with hail and thunder, southward across the above areas through the day. Isolated lightning has already been evident across NW England, Wales and NE Scotland so far this morning, thunderstorms will develop more widely / become more numerous through the day as surface heating beneath steep lapse rates creates strong convection - higher cloud tops for charge separation to occur. Vertical shear will be too weak and surface airmass too cold and dry for any severe weather today. Heavier showers and thunderstorms maybe accompanied by hail and gusty winds.

[MP-R]

Noticed a strike appear over south Wales recently. Also got woken up by torrential rain at about 6am this morning. Bit more breeze today so any cells probably going to move through quicker than of late.

[Arnie Pie]

Sharp active cells across to the West in Mid Wales atm....Heading this way

Were out for most of the day....but will leave a West facing camera running....Just in case!

Edit: Welsh cells seem to be slipping to the south of the area....line of cells in N wales might be of more interest

Edited April 29, 2016 by Arnie Pie

[MP-R]

Vicious downpour just moved through here with really gusty winds and sheets of rain. No thunder yet but sky blackening to the west again,

[Evening thunder]

Nice little hail shower just passed through here.

[Arnie Pie]

Nice hail core over Barr Beacon to the North of the city atm

Shopping can wait!....Cell over Wolverhampton

 

Edited April 29, 2016 by Arnie Pie

[Stuart]

FRI 29 APR 2016: UPDATE 10:24 UTC

Low-end (near 30% chance) SLGTs added to highlight areas with greatest potential for lightning activity. Over England, instability is greatest across Midlands/West Country to The Wash, but with much stronger shear to the SE, and hence the extension of the SLGT into SE England where DLS may compensate for lower CAPE

 

http://www.convectiveweather.co.uk/

[MP-R]

Strikes just north and northeast of Bristol. Haven't heard anything here but it's looked threatening that way a few times.

[Harry]

Second flash and rumble today from yet another wintry deluge....... 

However, contrary to Estofex, UKASF and Nick F having this part of the world under a lightning zone, I stupidly opted to follow the MetO's forecast last night which stated generally dry with cloud towards south coast and which made not a single reference to showers! I therefore left my coat and umbrella at home....fuming!

Edited April 29, 2016 by Harry

[Harry]

BLIMEY! In the last few minutes an extremely bright flash of lightning and bomb like crash of thunder, complete with torrential snow/soft hail.

Been a great week this week

[Daniel*]

OMG what we've had here hail the size of marbles

Edited April 29, 2016 by Daniel*

[Daniel*]

17 minutes ago, Harry said:

BLIMEY! In the last few minutes an extremely bright flash of lightning and bomb like crash of thunder, complete with torrential snow/soft hail.

Been a great week this week

I gather you are in central London? It scared the hell out of me sounded like an explosion extremely nearby. 2 Thunderstorms on the trot not bad, the hail storm provided the biggest covering greater than the winter season. 

Edited April 29, 2016 by Daniel*

[Sainsbo]

Can't remember seeing hailstones that large before, especially this time of year. Hailstones easily 1cm in diameter, a couple of them probably getting closer to 2!

Edited April 29, 2016 by Sainsbo

[East_England_Stormchaser91]

Pretty much every shower over the last few days has dodged me or died over me! Hopefully will get something in a bit. 

Would rather be in somewhere like Arkansas right now where the entire state is under a huge MCS as we speak. Can't wait for a bit of warmth over here too. This weather in late April just doesn't cut it for me. 

Edited April 29, 2016 by East_England_Stormchaser91

[Raidan]

A few showers here nothing heavy but second day in a row where there have been sferics just north of here but nothing actually here bit annoying.

[alexisj9]

4 minutes ago, East_England_Stormchaser91 said:

Pretty much every shower over the last few days has dodged me or died over me! Hopefully will get something in a bit. 

Would rather be in somewhere like Arkansas right now where the entire state is under a huge MCS as we speak. Can't wait for a bit of warmth over here too. This weather in late April just doesn't cut it for me. 

Wow that's a big storm.

[East_England_Stormchaser91]

8 minutes ago, alexisj9 said:

Wow that's a big storm.

It's a monster alright :O 

 

Sun out here now after the annoying remnants of a decayed shower. Come on, let's have a rumble before the evening is out! 

[Gordon Webb]

yep that band or rain that in northern england this morning which I thought might make it down to me has fixzled to just cloud seems to be nothing on the horizion either at the moment

[Harry]

1 hour ago, Daniel* said:

I gather you are in central London? It scared the hell out of me sounded like an explosion extremely nearby. 2 Thunderstorms on the trot not bad, the hail storm provided the biggest covering greater than the winter season. 

I am yes, Cannon Street. 

Seems like this part of the world has been a breeding ground today - new cells erupted about 15-30 mins ago and rushing eastwards across Essex/Kent.

Edited April 29, 2016 by Harry

[Gordon Webb]

well that line of showers/storms over London certainly didn't hang about did it

[Dami]

honestly gordon you should move to bedford. We don't do storms or thunder and it only hails about twice a year. That is if you like constant wind and bright sun shine.

[weather09]

Another day of CAPE progs, when viewed in isolation, giving only partial view of actual convective potential, with greatest lightning activity occurring over south and SE where weakest instability/less steep mid-levels was modeled.  Can take into consideration CAPE outputs not being so clear-cut - modeled instability in this case being tied to steepest lapse rates/coldest air aloft - but it appears it's more to do with the support aloft making the most of a weakly unstable environment, as was mentioned by Dan in his forecast. Appears strong left-exit jet and dry slot in mid-upper levels (per recent WV imagery as well as chart below) across the region, together with shortwave trough, increased instability and provided forcing for ascent, and increased bulk shear through the mid-level, overall supporting cell development.  Might explain the one or two sig. hail reports.  

  

Edited April 29, 2016 by weather09

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sat 30 Apr 2016 - 05:59 UTC Sun 01 May 2016

ISSUED 16:21 UTC Fri 29 Apr 2016

ISSUED BY: Dan

Sharpening upper trough and associated cold pool in the mid-levels will continue to clear eastwards from eastern Britain on Saturday; the approaching rear-side jet will serve to increase DLS from the west later in the day, accompanied by rising heights as ridging develops. This then provides a narrow window (spatially) for deep convection to occur.

Nonetheless, scattered showers will develop during the day in response to diurnal heating and steep lapse rates, particularly focussed late afternoon/early evening along zones of low-level wind convergence given fairly slack flow, perhaps with some organisation as DLS increases. Some sporadic/isolated lightning is likely, especially so in a zone from Lincolnshire down to the Home Counties / London / SE England (highlighted by a second LOW for clarity), but overall potential is considered below SLGT threshold. Given steep lapse rates and cold air aloft, numerous incidents of small hail / graupel are once again likely.

http://www.convectiveweather.co.uk/forecast.php?date=2016-04-30

[BornFromTheVoid]

Had some hail earlier the size of marbles with a few strikes too. The large hailstones are at the start of the video.

 

Here's a pic of a cell to the south west of here, currently over my parents where they said they saw the biggest hailstones they've seen, a little smaller than golf balls, and loads of thunder.

.